Components and catalysts for the polymerization of olefins

ABSTRACT

Catalyst component for the polymerization of olefins obtainable by contacting: (i) a magnesium halide, or a suitable precursor; (ii) a monofunctional electron donor compound (MD) selected from ethers, esters, amines or ketones, used in such amounts to have Mg/MD molar ratios of at least 50; (iii) a titanium compound of formula Ti(ORI)n-yXy, where n is the valence of titanium, y is a number between 1 and n, X is halogen, and RI is a C1-C15 hydrocarbon group and, optionally, (iv) an electron donor compound (ED). The said catalyst component shows improved activity in the polymerization of olefins.

[0001] The present invention relates to catalyst components for thepolymerization of olefins, to the catalyst obtained therefrom and to theuse of said catalysts in the (co)polymerization of olefins CH₂═CHR inwhich R is hydrogen or a hydrocarbyl radical with 1-12 carbon atoms. Inparticular the present invention relates to catalyst components,suitable for the (co)polymerization of olefins, comprising Mg, Ti,halogen and, optionally, an electron donor compound, that are obtainableby the use of a specific procedure. Said catalyst components are endowedwith high activity and stereospecificity when used in the(co)polymerization of propylene or higher alpha olefins. In thepolyolefin field Ziegler-Natta supported catalysts are customarily usedfor the preparation of homo or copolymers of olefins such as ethylene,propylene, butene-1 and so forth. One of the key requirements of thesupported catalysts used for the preparation of propylene polymers isthe capability of giving high yields coupled with highstereospecificity. The use of electron donor compounds in thepreparation of the Ziegler/Natta catalysts comprising a titaniumcompound on a magnesium-containing support is very well known. Suchelectron donor compounds are very often used in order to increase thestereospecificity of the catalyst in particular when the polymerizationof prochiral olefins is carried out. Generally, in order to achieve thedesired effect, the electron donor compound is used in such amounts thatat the end of the preparation process an appreciable and effectiveamount of it remains on the catalyst component. In order to obtain theexplained effect the electron donor compounds generally disclosed in theart are mono or polyfunctional ethers, esters and amines. Sometimes, asdisclosed in WO99/57160, is used a combination of two or more electrondonor compounds in order to obtain a catalyst endowed with specificproperties. Also in this case however, the amounts of donor and thepreparation conditions are selected in such a way of having, on thefinal catalyst, a substantive amount of both donors. We have nowsurprisingly found that certain supported catalyst components obtainableby a specific preparation procedure are capable to give increased yieldsover the catalysts of the prior art. The specific procedure comprisesthe use of such a low amount of certain electron donor compounds that atthe end of the preparation process it may also be not present on thefinal catalyst component. The catalyst component of the invention,however, results to be greatly improved with respect to the catalyststhat have not been contacted with such electron donor compound.

[0002] It is therefore an object of the present invention a catalystcomponent for the polymerization of olefins comprising Ti, Mg, andhalogen obtainable by contacting:

[0003] (i) a magnesium halide, or a suitable precursor,

[0004] (ii) a monofunctional electron donor compound (MD) selected fromethers, esters, amines or ketones, used in such amounts to have Mg/MDmolar ratios of at least 50;

[0005] (iii) a titanium compound of formula Ti(OR^(I))_(n-y)X_(y), wheren is the valence of titanium, y is a number between 1 and n, X ishalogen, and R^(I) is a C1-C15 hydrocarbon group and, optionally,

[0006] (iv) an electron donor compound (ED).

[0007] Preferably, the catalyst component is obtainable by a procedurecomprising contacting a magnesium halide, or a suitable precursor, witha titanium compound of formula Ti(OR^(I))_(n-y)X_(y), where n is thevalence of titanium, y is a number between 1 and n, X is halogen, andR^(I) is a C1-C15 hydrocarbon group in the presence of a monofunctionalelectron donor compound (MD) selected from ethers, esters, amines orketones, used in such amounts to have Mg/MD molar ratios of at least 50.Preferably the monofunctional electron donor compound (MD) is selectedfrom esters or ethers and, in particular from esters of monocarboxylicaromatic or aliphatic acids. Particularly preferred are the esters ofmonocarboxylic aromatic acids such as ethylbenzoate, n-butylbenzoate,p-methoxy ethylbenzoate, p-ethoxy ethylbenzoate, isobutylbenzoate, ethylp-toluate. Among monoethers particularly preferred are the aliphaticethers and in particular the cyclic ethers such as tetrahydrofurane andtetrahydropyran.

[0008] As explained above, such monofunctional electron donor compoundis used in amount such that the ratio Mg/MD molar ratio is at least 50.Preferably, such ratio is higher than 60 and more preferably higher than70. The preferred titanium compounds used in the catalyst component ofthe present invention are TiCl₄ and TiCl₃; furthermore, alsoTi-haloalcoholates of formula Ti(OR)_(n-y)X_(y) can be used, where n isthe valence of titanium, y is a number between 1 and n−1 X is halogenand R is a hydrocarbon radical having from 1 to 10 carbon atoms. Themagnesium dihalide can be used as such or in the form of a suitableprecursor. Particularly preferred is the use of the magnesium dihalidein active form or of a its suitable precursor. The magnesium halide inactive form is preferably MgCl₂ which is widely known from the patentliterature as a support for Ziegler-Natta catalysts. Patents U.S. Pat.No. 4,298,718 and U.S. Pat. No. 4,495,338 were the first to describe theuse of these compounds in Ziegler-Natta catalysis. It is known fromthese patents that the magnesium dihalides in active form used assupport or co-support in components of catalysts for the polymerizationof olefins are characterized by X-ray spectra in which the most intensediffraction line that appears in the ASTM-card reference of the spectrumof the non-active halide is diminished in intensity and broadened. Inthe X-ray spectra of preferred magnesium dihalides in active form saidmost intense line is diminished in intensity and replaced by a halowhose maximum intensity is displaced towards lower angles relative tothat of the most intense line. One method for obtaining magnesiumchloride in active form comprises for example the reaction of magnesiumdialkyl compounds or Grignard compounds with suitable chlorinatingagents such as hydrogen chloride or halogenated aluminumalkyls likediethylaluminum chloride. The so obtained magnesium chloride is thenreacted with the titanium compound (preferably an excess of TiCl₄ at atemperature of about 80 to 135° C. is used) and the electron donorcompound MD in order to obtain the catalyst component of the invention.It constitutes a preferred embodiment however the preparation of thecatalyst component in which is used a magnesium halide precursor whichis then converted into the magnesium dihalide during the reaction withthe titanium compound. According to a preferred method, the solidcatalyst component can be prepared by reacting a titanium compound offormula Ti(OR^(I))_(4-y)X_(y), preferably TiCl₄, where y is a numberbetween 1 and 4, and X and R^(I) have the meaning previously explained,with a magnesium chloride deriving from an adduct of formulaMgCl₂•pR^(II)OH, where p is a number between 0.1 and 6, preferably from2 to 3.5, and R^(II) is a hydrocarbon radical having 1-18 carbon atoms.The adduct can be suitably prepared in spherical form by mixing alcoholand magnesium chloride in the presence of an inert hydrocarbonimmiscible with the adduct, operating under stirring conditions at themelting temperature of the adduct (100-130° C.). Then, the emulsion isquickly quenched, thereby causing the solidification of the adduct inform of spherical particles. Examples of spherical adducts preparedaccording to this procedure are described in U.S. Pat. No. 4,399,054 andU.S. Pat. No. 4,469,648. The so obtained adduct can be directly reactedwith the Ti compound or it can be previously subjected to thermalcontrolled dealcoholation (80-130° C.) so as to obtain an adduct inwhich the number of moles of alcohol is generally lower than 3preferably between 0.1 and 2.5. The reaction with the Ti compound can becarried out by suspending the adduct (dealcoholated or as such) in coldTiCl₄; the mixture is heated up to 80-130° C. and kept at thistemperature for 0.5-2 hours. The treatment with TiCl₄ can be carried outone or more times. The electron donor compound MD can be addedseparately to the MgCl₂-alcohol adduct or, preferably, during thetreatment (preferably the first) with TiCl₄ In this embodiment the MD ispreferably added to the mixture of TiCl₄ and MgCl₂-alcohol adduct at atemperature ranging from −15 to 15° C., preferably from −10 to 10° C. Asexplained above the temperature of the system is then raised to 80-130°C. and kept at this temperature for 0.5-2 hours. After that, the slurryis separated off and the solid phase can be subject to furthertreatments with TiCl₄. When a stereospecific catalyst is to be prepared,it may be necessary to introduce a further electron donor compound (ED),different from MD, on the catalyst component. The ED compound can beadded at any stage of the preparation process but at least a firstaliquot of the total amount is preferably added during the first contacttreatment of TiCl₄, MgCl₂-alcohol adduct and MD compound. It isespecially preferred the addition of the ED compound after the additionof TiCl₄, MgCl₂-alcohol adduct and MD when the mixture is being heatedup. It is particularly preferred to carry out the said addition attemperatures of the mixture ranging from 20 to 100° C. preferably from30 to 90° C. The ED compound is preferably selected from the groupconsisting of difunctional electron donor compounds such as diesters,diketones, diammines and diethers. Preferably it is selected fromdiethers and diesters of dicarboxylic acids. Particularly preferred arethe compounds belonging to the class of the 1,3-diethers. In particular,preferred 1,3-diethers are those of formula (I)

[0009] where R^(I) and R^(II) are the same or different and are hydrogenor linear or branched C₁-C₁₈ hydrocarbon groups which can also form oneor more cyclic structures; R^(III) groups, equal or different from eachother, are hydrogen or C₁-C₁₈ hydrocarbon groups; R^(IV) groups equal ordifferent from each other, have the same meaning of R^(III) except thatthey cannot be hydrogen; each of R^(I) to R^(IV) groups can containheteroatoms selected from halogens, N, O, S and Si.

[0010] Preferably, R^(IV) is a 1-6 carbon atom alkyl radical and moreparticularly a methyl while the R^(III) radicals are preferablyhydrogen. Moreover, when R^(I) is methyl, ethyl, propyl, or isopropyl,R^(II) can be ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl,isopentyl, 2-ethylhexyl, cyclopentyl, cyclohexyl, methylcyclohexyl,phenyl or benzyl; when R¹ is hydrogen, R^(II) can be ethyl, butyl,sec-butyl, tert-butyl, 2-ethylhexyl, cyclohexylethyl, diphenylmethyl,p-chlorophenyl, 1-naphthyl, 1-decahydronaphthyl; R^(I) and R^(II) canalso be the same and can be ethyl, propyl, isopropyl, butyl, isobutyl,tert-butyl, neopentyl, phenyl, benzyl, cyclohexyl, cyclopentyl.

[0011] Specific examples of ethers that can be advantageously usedinclude: 2-(2-ethylhexyl)-1,3-dimethoxypropane,2-isopropyl-1,3-dimethoxypropane, 2-butyl-1,3-dimethoxypropane,2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-1,3-dimethoxypropane,2-phenyl-1,3-dimethoxypropane, 2-tert-butyl-1,3-dimethoxypropane,2-cumyl-1,3-dimethoxypropane, 2-(2-phenylethyl)-1,3-dimethoxypropane,2-(2-cyclohexylethyl)-1,3-dimethoxypropane,2-(p-chlorophenyl)-1,3-dimethoxypropane,2-(diphenylmethyl)-1,3-dimethoxypropane,2(1-naphthyl)-1,3-dimethoxypropane,2(p-fluorophenyl)-1,3-dimethoxypropane,2(1-decahydronaphthyl)-1,3-dimethoxypropane,2(p-tert-butylphenyl)-1,3-dimethoxypropane,2,2-dicyclohexyl-1,3-dimethoxypropane, 2,2-diethyl-1,3-dimethoxypropane,2,2-dipropyl-1,3-dimethoxypropane, 2,2-dibutyl-1,3-dimethoxypropane,2,2-diethyl-1,3-diethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane,2,2-dipropyl-1,3-diethoxypropane, 2,2-dibutyl-1,3-diethoxypropane,2-methyl-2-ethyl-1,3-dimethoxypropane,2-methyl-2-propyl-1,3-dimethoxypropane,2-methyl-2-benzyl-1,3-dimethoxypropane,2-methyl-2-phenyl-1,3-dimethoxypropane,2-methyl-2-cyclohexyl-1,3-dimethoxypropane,2-methyl-2-methylcyclohexyl-1,3-dimethoxypropane,2,2-bis(p-chlorophenyl)-1,3-dimethoxypropane,2,2-bis(2-phenylethyl)-1,3-dimethoxypropane,2,2bis(2-cyclohexylethyl)-1,3-dimethoxypropane,2-methyl-2-isobutyl-1,3-dimethoxypropane,2-methyl-2-(2-ethylhexyl)-1,3-dimethoxypropane,2,2-bis(2-ethylhexyl)-1,3-dimethoxypropane,2,2-bis(p-methylphenyl)-1,3-dimethoxypropane,2-methyl-2-isopropyl-1,3-dimethoxypropane,2,2-diisobutyl-1,3-dimethoxypropane, 2,2-diphenyl-1,3-dimethoxypropane,2,2-dibenzyl-1,3-dimethoxypropane,2-isopropyl-2-cyclopentyl-1,3-dimethoxypropane,2,2-bis(cyclohexylmethyl)-1,3-dimethoxypropane,2,2-diisobutyl-1,3-diethoxypropane, 2,2-diisobutyl-1,3-dibutoxypropane,2-isobutyl-2-isopropyl-1,3-dimetoxypropane,2,2-di-sec-butyl-1,3-dimetoxypropane,2,2-di-tert-butyl-1,3-dimethoxypropane,2,2-dineopentyl-1,3-dimethoxypropane,2-iso-propyl-2-isopentyl-1,3-dimethoxypropane,2-phenyl-2-benzyl-1,3-dimetoxypropane,2-cyclohexyl-2-cyclohexylmethyl-1,3-dimethoxypropane.

[0012] Furthermore, particularly preferred are the 1,3-diethers offormula (II):

[0013] where the R^(VI) radicals equal or different are hydrogen;halogens, preferably Cl and F; C₁-C₂₀ alkyl radicals, linear orbranched; C₃-C₂₀ cycloalkyl, C₆-C₂₀ aryl, C₇-C₂₀ alkylaryl and C₇-C₂₀aralkyl radicals, optionally containing one or more heteroatoms selectedfrom the group consisting of N, O, S, P, Si and halogens, in particularCl and F, as substitutes for carbon or hydrogen atoms, or both; theradicals R^(III) and R^(IV) are as defined above for formula (I).

[0014] Specific examples of compounds comprised in formulae (II) and(III) are:

[0015] 1,1-bis(methoxymethyl)-cyclopentadiene;

[0016] 1,1-bis(methoxymethyl)-2,3,4,5-tetramethylcyclopentadiene;

[0017] 1,1-bis(methoxymethyl)-2,3,4,5-tetraphenylcyclopentadiene;

[0018] 1,1-bis(methoxymethyl)-2,3,4,5-tetrafluorocyclopentadiene;

[0019] 1,1-bis(methoxymethyl)-3,4-dicyclopentylcyclopentadiene;

[0020] 1,1-bis(methoxymethyl)indene;1,1-bis(methoxymethyl)-2,3-dimethylindene;

[0021] 1,1-bis(methoxymethyl)-4,5,6,7-tetrahydroindene;

[0022] 1,1-bis(methoxymethyl)-2,3,6,7-tetrafluoroindene;

[0023] 1,1-bis(methoxymethyl)-4,7-dimethylindene;

[0024] 1,1-bis(methoxymethyl)-3,6-dimethylindene;

[0025] 1,1-bis(methoxymethyl)-4-phenylindene;

[0026] 1,1-bis(methoxymethyl)-4-phenyl-2-methylindene;

[0027] 1,1-bis(methoxymethyl)-4-cyclohexylindene;

[0028] 1,1-bis(methoxymethyl)-7-(3,3,3-trifluoropropyl)indene;

[0029] 1,1-bis(methoxymethyl)-7-trimethyisilylindene;

[0030] 1,1-bis(methoxymethyl)-7-trifluoromethylindene;

[0031] 1,1-bis(methoxymethyl)-4,7-dimethyl-4,5,6,7-tetrahydroindene;

[0032] 1,1-bis(methoxymethyl)-7-methylindene;

[0033] 1,1-bis(methoxymethyl)-7-cyclopenthylindene;

[0034] 1,1-bis(methoxymethyl)-7-isopropylindene;

[0035] 1,1-bis(methoxymethyl)-7-cyclohexylindene;

[0036] 1,1-bis(methoxymethyl)-7-tert-butylindene;

[0037] 1,1-bis(methoxymethyl)-7-tert-butyl-2-methylindene;

[0038] 1,1-bis(methoxymethyl)-7-phenylindene;

[0039] 1,1-bis(methoxymethyl)-2-phenylindene;

[0040] 1,1-bis(methoxymethyl)-1H-benz[e]indene;

[0041] 1,1-bis(methoxymethyl)-1H-2-methylbenz[e]indene;

[0042] 9,9-bis(methoxymethyl)fluorene;

[0043] 9,9-bis(methoxymethyl)-2,3,6,7-tetramethylfluorene;

[0044] 9,9-bis(methoxymethyl)-2,3,4,5,6,7-hexafluorofluorene;

[0045] 9,9-bis(methoxymethyl)-2,3-benzofluorene;

[0046] 9,9-bis(methoxymethyl)-2,3,6,7-dibenzofluorene;

[0047] 9,9-bis(methoxymethyl)-2,7-diisopropylfluorene;

[0048] 9,9-bis(methoxynethyl)-1,8-dichlorofluorene;

[0049] 9,9-bis(methoxymethyl)-2,7-dicyclopentylfluorene;

[0050] 9,9-bis(methoxymethyl)-1,8-difluorofluorene;

[0051] 9,9-bis(methoxymethyl)-1,2,3,4-tetrahydrofluorene;

[0052] 9,9-bis(methoxymethyl)-1,2,3,4,5,6,7,8-octahydrofluorene;

[0053] 9,9-bis(methoxymethyl)-4-tert-butylfluorene.

[0054] The diesters can be esters of aliphatic or aromatic dicarboxyilicacids. Among esters of aliphatic dicarboxylic acids particularlypreferred are the malonates, glutarates and succinates. Among malonates,particularly preferred are those of formula (III):

[0055] where R₁ is H or a C₁-C₂₀ linear or branched alkyl, alkenyl,cycloalkyl, aryl, arylalkyl or alkylaryl group, R₂ is a C₁-C₂₀ linear orbranched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group,R₃ and R₄, equal to, or different from, each other, are C₁-C₂₀ linear orbranched alkyl groups or C₃-C₂₀ cycloalkyl groups.

[0056] Preferably, R₃ and R₄ are primary, linear or branched C₁-C₂₀alkyl groups, more preferably they are primary branched C₄-C₂₀ alkylgroups such as isobutyl or neopentyl groups.

[0057] R₂ is preferably, in particular when R₁ is H, a linear orbranched C₃-C₂₀ alkyl, cycloalkyl, or arylalkyl group; more preferablyR₂ is a C₃-C₂₀ secondary alkyl, cycloalkyl, or arylalkyl group. Specificexamples of preferred monosubstituted malonate compounds are:dineopentyl 2-isopropylmalonate, diisobutyl 2-isopropylmalonate,di-n-butyl 2-isopropylmalonate, diethyl 2-dodecylmalonate, diethyl2-t-butylmalonate, diethyl 2-(2-pentyl)malonate, diethyl2-cyclohexylmalonate, dineopentyl 2-t-butylmalonate, dineopentyl2-isobutylmalonate, diethyl 2-cyclohexylmethylmalonate, dimethyl2-cyclohexylmethylmalonate. Specific examples of preferred disubstitutedmalonates compounds are: diethyl 2,2-dibenzylmalonate, diethyl2-isobutyl-2-cyclohexylmalonate, dimethyl 2-n-butyl-2-isobutylmalonate,diethyl 2-n-butyl-2-isobutylmalonate, diethyl2-isopropyl-2-n-butylmalonate, diethyl 2-methyl-2-isopropylmalonate,diethyl 2-isopropyl-2-isobutylmalonate, diethyl2-methyl-2-isobutylmalonate, diethyl 2-isobutyl-2-benzylmalonate.Preferred esters of aromatic dicarboxylic acids are selected from C₁-C₂₀alkyl or aryl esters phthalic acids, possibly substituted. The alkylesters of the said acids are preferred. Particularly preferred are theC₁-C₆ linear or branched alkyl esters. Specific examples are diethylphthalate, di-n-propyl phthalate, di-n-butyl phthalate, di-n-pentylphthalate, di-i-pentyl phthalate, bis(2-ethylhexyl) phthalate,ethyl-isobutyl phthalate, ethyl-n-butyl phthalate, di-n-hexyl phthalate,di-isobutylphthalate.

[0058] The electron donor compound ED is normally present in amountssuch as to give a Ti/ED molar ratio of higher than 1 and preferablyhigher than 1.5. As far as the content of the MD compound is concerned,as explained above, it is generally present in the catalyst componentsin amounts lower than 1% by weight with respect to the total weight ofthe solid catalyst components without solvent and preferably lower than0.5% by weight. In some instances the MD compound could also be notpresent on the solid catalyst component. When MD is present the molarratio ED/MD is higher than 10, preferably higher than 15 and morepreferably higher than 30. When prepared with the above preferred methodthe catalyst components of the invention show a surface area (by B.E.T.method) generally between 20 and 500 m²/g and preferably between 50 and400 m²/g, and a total porosity (by B.E.T. method) higher than 0.2 cm³/gpreferably between 0.2 and 0.6 cm³/g. The porosity (Hg method) due topores with radius up to 10,000 Å generally ranges from 0.3 to 1.5 cm³/g,preferably from 0.45 to 1 cm³/g. The solid catalyst components accordingto the present invention are converted into catalysts for thepolymerization of olefins by reacting them with suitable co-catalysts.Among them organoaluminum compounds are preferred. In particular, it isan object of the present invention a catalyst for the polymerization ofolefins CH₂═CHR, in which R is hydrogen or a hydrocarbyl radical with1-12 carbon atoms, comprising the product of the reaction between:

[0059] (i) a catalyst component for the polymerization of olefinscomprising Ti, Mg, halogen and optionally an electron donor compound(ED) obtainable by a procedure comprising contacting a magnesium halide,or a suitable precursor, with a titanium compound of formulaTi(OR^(I))_(n-y)X_(y), where n is the valence of titanium, y is a numberbetween 1 and n, X is halogen, and R^(I) is a C1-C15 hydrocarbon groupin the presence of a monofunctional electron donor compound (MD)selected from ethers, esters, amines or ketones, used in such amounts tohave Mg/MD molar ratios of at least 50;

[0060] (ii) an alkylaluminum compound and, optionally,

[0061] (iii) one or more electron-donor compounds (external donor).

[0062] The alkyl-Al compound (b) is preferably selected from thetrialkyl aluminum compounds such as for example triethylaluminum,triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum,tri-n-octylaluminum. It is also possible to use mixtures oftrialkylaluminum's with allylaluminum halides, alkylaluminum hydrides oralkylaluminum sesquichlorides such as AlEt₂Cl and Al₂Et₃Cl₃.

[0063] The external donor (c) can be selected among silicon compounds,ethers, esters such as ethyl 4-ethoxybenzoate, amines, heterocycliccompounds and particularly 2,2,6,6-tetramethyl piperidine, and ketones.One particular class of preferred external donor compounds is that ofsilicon compounds of formula R_(a) ⁵R_(b) ⁶Si(OR⁷)_(c), where a and bare integer from 0 to 2, c is an integer from 1 to 3 and the sum (a+b+c)is 4; R⁵, R⁶, and R⁷, are alkyl, cycloalkyl or aryl radicals with 1-18carbon atoms optionally containing heteroatoms. Particularly preferredare the silicon compounds in which a is 1, b is 1, c is 2, at least oneof R⁵ and R⁶ is selected from branched alkyl, cycloalkyl or aryl groupswith 3-10 carbon atoms optionally containing heteroatoms and R⁷ is aC1-C10 alkyl group, in particular methyl. Examples of such preferredsilicon compounds are methylcyclohexyldimethoxysilane,diphenyldimethoxysilane, methyl-t-butyldimethoxysilane,dicyclopentyldimethoxysilane,2-ethylpiperidinyl-2-t-butyldimethoxysilane,1,1,1,trifluoropropyl-metil-dimethoxysilane and1,1,1,trifluoropropyl-2-ethylpiperidinyl-dimethoxysilane. Moreover, arealso preferred the silicon compounds in which a is 0, c is 3, R⁶ is abranched alkyl or cycloalkyl group, optionally containing heteroatoms,and R⁷ is methyl. Examples of such preferred silicon compounds arecyclohexyltrimethoxysilane, t-butyltrimethoxysilane andthexyltrimethoxysilane. The electron donor compound (c) is used in suchan amount to give a molar ratio between the organoaluminum compound andsaid electron donor compound (c) of from 0.1 to 500, preferably from 1to 300 and more preferably from 3 to 100. As previously indicated, thesaid catalyst are suitable for preparing a broad range of polyolefinproducts. In particular they are suitable for preparing isotacticpolypropylenes and crystalline copolymers of propylene and ethyleneand/or other alpha-olefins having a content of units derived frompropylene of higher than 85% by weight. However, they can also be usedto prepare, for example, high density ethylene polymers APE, having adensity higher than 0.940 g/cm³), comprising ethylene homopolymers andcopolymers of ethylene with alpha-olefins having 3-12 carbon atoms;elastomeric copolymers of ethylene and propylene and elastomericterpolymers of ethylene and propylene with smaller proportions of adiene having a content by weight of units derived from ethylene ofbetween about 30 and 70%; impact resistant polymers of propyleneobtained by sequential polymerization of propylene and mixtures ofpropylene with ethylene, containing up to 30% by weight of ethylene;copolymers of propylene and 1-butene having a number of units derivedfrom 1-butene of between 10 and 40% by weight. In view of the above, itconstitutes a further object of the present invention a process for the(co)polymerization of olefins CH₂═CHR, in which R is hydrogen or ahydrocarbyl radical with 1-12 carbon atoms, carried out in the presenceof the catalyst described above. The olefins can be selected inparticular from ethylene, propylene, butene-1,4-methyl-1-pentene,hexene-1, octene-1. The polymerization process using the catalyst of theinvention can be carried out according to known techniques either inliquid or gas phase using, for example, the known technique of thefluidized bed or under conditions wherein the polymer is mechanicallystirred. The catalyst of the present invention can be used as such inthe polymerization process by introducing it directly into the reactor.However, it constitutes a preferential embodiment the prepolymerizationof the catalyst with an olefin. In particular, it is especiallypreferred prepolymerizing ethylene, or propylene or mixtures thereofwith one or more α-olefins, said mixtures containing up to 20% by moleof α-olefin, forming amounts of polymer from about 0.1 g per gram ofsolid component up to about 1000 g per gram of solid catalyst component.The pre-polymerization step can be carried out at temperatures from 0 to80° C. preferably from 5 to 50° C. in liquid or gas-phase. Thepre-polymerization step can be performed in-line as a part of acontinuos polymerization process or separately in a batch process. Thebatch pre-polymerization of the catalyst of the invention with ethylenein order to produce an amount of polymer ranging from 0.5 to 20 g pergram of catalyst component is particularly preferred. The mainpolymerization process in the presence of catalysts obtained from thecatalytic components of the invention can be carried out according toknown techniques either in liquid or gas phase using for example theknown technique of the fluidized bed or under conditions wherein thepolymer is mechanically stirred. Preferably the process is carried outin the gas phase. Examples of gas-phase processes wherein it is possibleto use the spherical components of the invention are described inWO92/21706, U.S. Pat. No. 5,733,987 and WO93/03078. In this processes apre-contacting step of the catalyst components, a pre-polymerizationstep and a gas phase polymerization step in one or more reactors in aseries of fluidized or mechanically stirred bed are comprised.Therefore, in the case that the polymerization takes place in gas-phase,the process of the invention is suitably carried out according to thefollowing steps:

[0064] (a) contact of the catalyst components in the absence ofpolymerizable olefin or optionally in the presence of said olefin inamounts not greater than 20 g per gram of the solid component (A);

[0065] (b) pre-polymerization of ethylene or mixtures thereof with oneor more α-olefins, said mixtures containing up to 20% by mole ofα-olefin, forming amounts of polymer from about 0.1 g per gram of solidcomponent (A) up to about 1000 g per gram;

[0066] (c) gas-phase polymerization of one or more olefins CH₂═CHR, inwhich R is hydrogen or a hydrocarbon radical having 1-10 carbon atoms,in one or more fluidized or mechanically stirred bed reactors using thepre-polymer-catalyst system coming from (b).

[0067] As mentioned above, the pre-polymerization step can be carriedout separately in batch. In this case, the pre-polymerized catalyst ispre-contacted according to step (a) with the aluminum alkyl and thendirectly sent to the gas-phase polymerization step (c).

[0068] The Molecular Weight of the polymer is normally controlled usinghydrogen or other agents capable to regulate the Molecular Weight. Ifneeded the polymerization process of the invention can be performed intwo or more reactors working under different conditions and optionallyby recycling, at least partially, the polymer which is formed in thesecond reactor to the first reactor. As an example the two or morereactors can work with different concentrations of molecular weightregulator or at different polymerization temperatures or both. Thefollowing examples are given in order to further describe the presentinvention in a non-limiting manner.

[0069] Characterization

[0070] Determination of X.I.

[0071] 2.5 g of polymer were dissolved in 250 ml of o-xylene understirring at 135° C. for 30 minutes, then the solution was cooled to 25°C. and after 30 minutes the insoluble polymer was filtered. Theresulting solution was evaporated in nitrogen flow and the residue wasdried and weighed to determine the percentage of soluble polymer andthen, by difference, the X.I. %.

[0072] MIE: Melt Index measured at 190° C. according to ASTM D-1238condition “E”.

[0073] MIL: Melt Index measured at 190° C. according to ASTM D-1238condition “L”.

EXAMPLES Propylene General Polymerization Procedure

[0074] In a 4-liter autoclave, purged with nitrogen flow at 70° C. fortwo hours, 75 ml of anhydrous hexane containing 760 mg of AlEt₃, 63 mgof cyclohexylmethyldimethoxysilane and 10 mg of solid catalyst componentwere introduced in propylene flow at 30° C. The autoclave was closed.1.5 Nl of hydrogen were added and then, under stirring, 1.2 Kg of liquidpropylene were fed. The temperature was raised to 70° C. in five minutesand the polymerization was carried out at this temperature for twohours. The non-reacted propylene was removed, the polymer was recoveredand dried at 70° C. under vacuum for three hours and then weighed andanalyzed for the determination of the Mg residues by which the activityof the catalyst is calculated.

Ethylene General Polymerization Procedure

[0075] Into a 4 liters stainless steel autoclave degassed under N₂stream at 70° C. for one hour, 0.02 g of spherical catalyst component,13.7 mg of cyclohexylmethyldimethoxysilane and 0.5 g of AlEt₃ at roomtemperature were introduced.

[0076] The autoclave was closed and then 250 ml of propane and 20 g ofpropylene were added keeping temperature at 30° C. The polymerisationstep was stopped after 45 minutes, totally discharging propane andpropylene. After the introduction of 1.6 liters of propane, thetemperature was raised to 75° C. and 3 bar of H₂ and 7 bar of ethylenewere fed into the reactor. During the polymerization ethylene was fed tokeep the pressure constant. After 3 hours the polymerization wasdiscontinued and the spherical polymer was collected and dried at 70° C.under a nitrogen flow.

Example 1 Preparation of the Spherical Support (MgCl₂/EtOH Adduct)

[0077] The adduct of magnesium chloride and alcohol was preparedaccording to the method described in Example 2 of U.S. Pat. No.4,399,054, but operating at 2000 rpm instead of 10,000 rpm. The soobtained adduct contained approximately 3 mol of alcohol.

Preparation of the Solid Component

[0078] Into a 2 L four-necked glass reactor, equipped with a mechanicalstirrer and a thermometer, purged with nitrogen, 1500 mL of TiCl₄ wereintroduced and cooled at −5° C. While stirring, 45 g of microspheroidalMgCl₂*2.9C₂H₅OH and 2.8 mmol of ethylbenzoate were added, so that Mg/EBmolar ratio was 70. The suspension was heated up to 40° C. and 17.3 mmolof diisobutylphtalate were added, so that Mg/DIBP molar ratio was 8.5.The temperature was raised to 100° C. and maintained for 60 min. Then,the stirring was discontinued, the solid product was allowed to settleat 100° C. for 15 minutes and the supernatant liquid was siphoned off.

[0079] Then 1500 mL of fresh TiCl₄ were added on the solid product. Themixture was reacted at 120° C. for 30 min and than the stirring wasstopped and the reactor cooled to 100° C.; the solid product was allowedto settle at 100° C. for 15 min and the supernatant liquid was siphonedoff. Once again, 1500 mL of fresh TiCl₄ were added on the solid product.The mixture was reacted at 120° C. for 30 min and than the stirring wasstopped and the reactor cooled to 100° C.; the solid product was allowedto settle at 100° C. for 15 min and the supernatant liquid was siphonedoff. The solid was washed with 6×600 mL of anhydrous hexane three timesat 60° C. and three times at room temperature. Finally, the solid wasdried under vacuum, analyzed and tested. The analysis of the catalystcomponent and the results in the polymerization of propylene accordingto the above reported procedure are shown in table 1.

Example 2

[0080] The same procedure disclosed in Example 1 was repeated with thedifference that the amount of EB used was such that the Mg/Ethylbenzoate molar ratio was 90. The analysis of the catalyst component andthe results in the polymerization of propylene according to the abovereported procedure are shown in table 1.

Comparison Example 1

[0081] The same procedure disclosed in Example 1 was repeated with thedifference that EB was not used. The analysis of the catalyst componentand the results in the polymerization of propylene according to theabove reported procedure are shown in table 1.

Example 3 Preparation of a MgCl₂*2.2C₂H₅OH Adduct

[0082] The MgCl₂/EtOH adduct containing approximately 3 mol of alcoholprepared according to the same procedure disclosed in Example 1 wassubject to temperatures that gradually increased from 50° C. to 100° C.in nitrogen current until the alcohol content is reduced to 2.2 molesper mole of MgCl₂.

Preparation of the Solid Component

[0083] Into a 1L four-necked glass reactor, equipped with a mechanicalstirrer and a thermometer, purged with nitrogen, 800 mL of TiCl₄ wereintroduced and cooled at −5° C. While stirring, 32 g of the saidmicrospheroidal MgCl₂*2.2C₂H₅OH and 3.3 mmol of ethylbenzoate were addedso that Mg/EB molar ratio was 50. The suspension was heated up to 80° C.and 18.8 mmol of diisobuthylphtalate were added, so that Mg/DIBP molarratio was 8.5. The temperature was raised to 100° C. and maintained for120 min. Then, the stirring was discontinued, the solid product wasallowed to settle at 100° C. for 15 minutes and the supernatant liquidwas siphoned off. Then 800 mL of fresh TiCl₄ were added on the solidproduct. The mixture was reacted at 120° C. for 30 min and than thestirring was stopped and the reactor cooled to 100° C.; the solidproduct was allowed to settle at 100° C. for 15 min and the supernatantliquid was siphoned off. Once again, 800 mL of fresh TiCl₄ were added onthe solid product. The mixture was reacted at 120° C. for 30 min andthan the stirring was stopped and the reactor cooled to 100° C.; thesolid product was allowed to settle at 100° C. for 15 min and thesupernatant liquid was siphoned off. The solid was washed with 6×600 mLof anhydrous hexane three times at 60° C. and three times at roomtemperature. Finally, the solid was dried under vacuum, analyzed andtested.

Example 4

[0084] The same procedure disclosed in Example 3 was repeated with thedifference that the amount of EB used was such that the Mg/Ethylbenzoate molar ratio was 90. The analysis of the catalyst component andthe results in the polymerization of propylene according to the abovereported procedure are shown in table 1.

Comparison Example 2

[0085] The same procedure disclosed in Example 3 was repeated with thedifference that EB was not used. The analysis of the catalyst componentand the results in the polymerization of propylene according to theabove reported procedure are shown in table 1.

Example 5

[0086] The same procedure disclosed in Example 3 was repeated with thedifference that tetrahydrofurane (THF) at Mg/THF molar ratio of 60 wasused instead of EB. Moreover, the DIBF was added (Mg/DIBF molar ratio 8)when the temperature of the mixture was 40° C. The analysis of thecatalyst component and the results in the polymerization of propyleneaccording to the above reported procedure are shown in table 1.

Example 6

[0087] The same procedure disclosed in Example 5 was repeated with thedifference that the amount of THF used was such that the Mg/THF molarratio was 90. The analysis of the catalyst component and the results inthe polymerization of propylene according to the above reportedprocedure are shown in table 1.

Example 7

[0088] The same procedure disclosed in Example 1 was repeated with thedifference that the MgCl₂/EtOH adduct containing approximately 3 mol ofalcohol was subject to temperatures that gradually increased from 50° C.to 100° C. in nitrogen current until the alcohol content is reduced toabout 1.1 moles per mole of MgCl₂. Moreover, that the amount of EB usedwas such that the Mg/Ethyl benzoate molar ratio was 60 and the DIBF wasadded in such an amount that the Mg/DIBF molar ratio was 16. Theanalysis of the catalyst component and the results in the polymerizationof ethylene according to the above reported procedure are shown in table1.

Comparison Example 3

[0089] The same procedure disclosed in Example 7 was repeated with thedifference that EB was not used. The analysis of the catalyst componentand the results in the polymerization of ethylene according to the abovereported procedure are shown in Table 1. TABLE 1 COMPOSITION C3⁻POLYMERIZATION Ti Mg Cl MD ED Solvent ED/MD ACTIVITY XI Example (% wt)(% wt) (% wt) (% wt) (% wt) (% wt) m.r. Kg/g (%) MIL 1 3.3 15.7 52 0.1 11 17.2 59.4 82.4 97.9 8.9 2 2.8 15.4 51 — 9.5 20.5 — 84.2 98.2 7.2Comp. 1 3.2 15.1 54 — 13.3 11 — 60.6 98.1 4.7 3 2.5 15.9 52.5 0.15 6.5519.5 23.6 70.5 98 4.8 4 3.3 17.3 58.2 0.15 7.85 9.75 28.2 76.7 97.8 10Comp. 2 2.6 16.7 60 — 9.3 13 — 54.8 97.9 16 5 3.51 18.1 63.5 0.23 10.113.1 64.6 97.9 5.6 6 3.76 18.7 66.2 — 8.7 21.4  11.35 66.8 97.8 7.8COMPOSITION C2⁻ POLYMERIZATION Ti Mg Cl MD ED ED/MD ACTIVITY (% wt) (%wt) (% wt) (% wt) (% wt) Solvent m.r. Kg/g MIE 7 4.4 16.2 60.4 0.8  2.18 3.17 38 0.1 Comp. 3 4.4 16 56.5 — 5.5 12.1 — 29 0.13

1. Catalyst component for the polymerization of olefins obtainable bycontacting: (i) a magnesium halide, or a suitable precursor, (ii) amonofunctional electron donor compound (MD) selected from ethers,esters, amines or ketones, used in such amounts to have Mg/MD molarratios of at least 50; (iii) a titanium compound of formulaTi(OR^(I))_(n-y)X_(y), where n is the valence of titanium, y is a numberbetween 1 and n, X is halogen, and R¹ is a C1-C15 hydrocarbon group and,optionally, (iv) an electron donor compound (ED).
 2. Catalyst componentaccording to claim 1 containing Mg, Ti and halogen obtainable by aprocedure comprising contacting a magnesium halide, or a suitableprecursor, with a titanium compound of formula Ti(OR^(I))_(n-y)X_(y),where n is the valence of titanium, y is a number between 1 and n, X ishalogen, and R^(I) is a C1-C15 hydrocarbon group in the presence of amonofunctional electron donor compound (MD) selected from ethers,esters, amines or ketones, used in such amounts to have Mg/MD molarratios of at least
 50. in which the monofunctional electron donorcompound (MD) is an ester or an ether.
 3. Catalyst component accordingto claim 1 in which the monofunctional electron donor compound (MD) isselected from esters of monocarboxylic aromatic or aliphatic acids. 4.Catalyst component according to claim 3 in which the monofunctionalelectron donor compound (MD) is selected from the group consisting ofethylbenzoate, n-butylbenzoate, p-methoxy ethylbenzoate, p-ethoxyethylbenzoate, isobutylbenzoate, ethyl p-toluate.
 5. Catalyst componentaccording to claim 1 in which the monofunctional electron donor compound(MD) is selected from aliphatic ethers.
 6. Catalyst component accordingto claim 5 in which the monofunctional electron donor compound (MD) istetrahydrofurane.
 7. Catalyst component according to claim 1 in whichthe Mg/MD molar ratio is higher than
 60. 8. Catalyst component accordingto claim 7 in which the Mg/MD molar ratio is higher than
 70. 9. Catalystcomponent according to claim 1 comprising a titanium compound selectedfrom the group consisting of TiCl₄, TiCl₃; and Ti-haloalcoholates offormula Ti(OR)_(n-y)X_(y) can be used, where n is the valence oftitanium, y is a number between 1 and n−1 X is halogen and R is ahydrocarbon radical having from 1 to 10 carbon atoms.
 10. Catalystcomponent according to claim 1 which is obtained by contacting atitanium compound of formula Ti(OR^(I))_(4-y)X_(y), where y is a numberbetween 1 and 4, and X and R^(I) have the meaning previously explainedwith an adduct of formula MgCl₂•pR^(II)OH, where p is a number between0.1 and 6 and with a preferably from 2 to 3.5, and R^(II) is ahydrocarbon radical having 1-18 carbon atoms and with a monofunctionalelectron donor compound (MD) selected from ethers, esters, amines orketones, used in such amounts to have Mg/MD molar ratios of at least 50.11. Catalyst component according to claim 10 in which the titaniumcompound is TiCl₄.
 12. Catalyst component according to claim 1 furthercomprising an electron donor compound (ED), different from MD. 13.Catalyst component according to claim 12 in which the ED compound isselected from the group consisting of difunctional electron donorcompounds such as diesters, diketones, diammines and diethers. 14.Catalyst component according to claim 13 in which the ED compound isselected from C₁-C₂₀ alkyl or aryl esters phthalic acids.
 15. Catalystcomponent according to claim 14 characterized in that the esters ofphtahlic acids are diethyl phthalate, di-n-propyl phthalate, di-n-butylphthalate, di-n-pentyl phthalate, di-i-pentyl phthalate,bis(2-ethylhexyl) phthalate, ethyl-isobutyl phthalate, ethyl-n-butylphthalate, di-n-hexyl phthalate, and di-isobutylphthalate.
 16. Catalystcomponent for the polymerization of olefins comprising a titaniumcompound a Mg-dihalide, a difunctional electron donor compound (ED)selected from diesters, diketones, diammines and diethers and amonofunctional electron donor compound (MD) selected from ethers,esters, amines or chetones, characterized in that the molar ratio ED/MDis higher than
 10. 17. Catalyst component according to claim 16 in whichthe Mg-dihalide is MgCl₂ in active form.
 18. Catalyst componentaccording to claim 16 in which the molar ratio ED/MD is higher than 15.19. Catalyst component according to claim 18 in which the molar ratioED/MD is higher than
 30. 20. Catalyst component according to claim 16 inwhich the MD compound is present in amounts lower than 1% by weight withrespect to the total weight of the solid catalyst components withoutsolvent.
 21. Catalyst component according to claim 20 in which the MDcompound is present in amounts lower than 0.5% by weight.
 22. Catalystfor the polymerization of olefins CH₂═CHR, in which R is hydrogen or ahydrocarbyl radical with 1-12 carbon atoms, comprising the product ofthe reaction between: (i) a catalyst component according to anyone ofthe preceding claims (ii) an alkylaluminum compound and, optionally,(iii) one or more electron-donor compounds (external donor). 23.Catalyst according to claim 22 in which the alkylaluminum compound isselected from the trialkyl aluminum compounds.
 24. Catalyst according toclaim 22 in which the external donor (c) is selected among siliconcompounds of formula R_(a) ⁵R_(b) ⁶Si(OR⁷)_(c), where a and b areinteger from 0 to 2, c is an integer from 1 to 3 and the sum (a+b+c) is4; R⁵, R⁶, and R⁷, are alkyl, cycloalkyl or aryl radicals with 1-18carbon atoms optionally containing heteroatoms.
 25. Process for the(co)polymerization of olefins CH₂═CHR, in which R is hydrogen or ahydrocarbyl radical with 1-12 carbon atoms, carried out in the presenceof the catalyst according to any of the previous claims 22-24.